----- Original Message -----
From: "Steve Thompson" <g8gsq@qsl.net>
To: <amps@contesting.com>
Sent: Friday, October 04, 2002 4:41 PM
Subject: Re: [Amps] skin effect
>
> ----- Original Message -----
> From: Steve M <wmoorejr@cox.net>
> To: Steve Thompson <g8gsq@qsl.net>; <amps@contesting.com>
> Sent: 04 October 2002 22:05
> Subject: Re: [Amps] skin effect
>
>
> > > > Steve,
> > > >
> > > > The advantage of regular stranded wire is flexability.
> > > > Litz wire is a special type of stranded wire that is used to reduce
> skin
> > > > effect.
> **Ok thanks.
> > > The longwave guys certainly love it - the key point is that the
strands
> > >are insulated from each other.
> **Insulated---ok, this is starting to make some sense.
> > >
> > > A lot of stranded wire is multiple cores of tinned copper - skin
effect
> > > means that, at hf upwards, the rf current flows in the tin plating
which
> > >is relatively lossy. You'd need to be sure that people were comparing
> like
> > > wires.
> **I'm not sure what some of them are comparing. hi hi **Ok on
> the tin being lossier than copper, but tin or copper regular stranded [not
> litz] has no advantage as to skin effect over same gauge solid tin or
> copper? Is this right?
> >
> I believe so, but I'm wide open to correction. I think there are effects
to
> consider with multi-strand insulated wire, much the same as with close
wound
> coils. I can't recall the detail, but current flowing in close adjacent
> wires tends to force the current into the centre of the wire, reducing the
> cross section of current flow and so increasing the loss. Somewhere I have
> some info. which relates to the effect in multi turn rx loop antennas.
***Thanks again. This seems to be a hard one to pin down.
>
> Once, as an experiment, I changed a coil in a 8877 6m tank circuit from
3/8"
> copper tube to (I think) 7x1mm enamelled wires twisted together. In simple
> terms, there was more cross section for the rf current but in practice the
> coil burnt out in a big way after a minute or so key down.
***I would have thought the 7x1mm wires being insulated would have acted
like litz wire and been more efficient.
>
> Steve
Steve wd0ct
>
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